Diagnostic and therapeutic procedures have been developed in which a catheter is transluminally advanced within a guide sheath or over a guidewire into various chambers of the human heart. The human heart includes a right ventricle, a right atrium, left ventricle, and left atrium. The right atrium is in fluid communication with the superior vena cava and the inferior vena cava. The tricuspid valve separates the right atrium from the right ventricle. The right atrium is separated from the left atrium by a septum that includes a thin membrane known as the fossa ovalis.
The left atrium is a difficult chamber of the heart to access with a catheter. One method of accessing the left atrium involves catheterization through the femoral vein into the right atrium, and subsequent penetration of the atrial septum to gain entry to the left atrium. Conventional transseptal medical devices used to penetrate this septum include a needle that is movable within an elongated dilator and/or sheath. The needle is maintained within the dilator until the assembly is positioned at the puncture location of the septum, and then is extended from the dilator to puncture the septum.
Conventional transseptal puncture procedures are conducted using X-ray and/or ultrasound imaging technology to facilitate guidance of the puncture device through the body and to the target location within the heart. Conventional X-ray based systems use electroanatomical maps which are virtual representations of the heart showing sensed electrical activity. Examples of such systems include the Carto® electroanatomic mapping system from Biosense Webster, Inc., Diamond Bar, Calif., and the EnSite NavX® system from Endocardial Solutions Inc., St. Paul, Minn. Unfortunately, X-ray imaging technology has a number of limitations, including limited anatomical visualization of the body and blood vessels, limited ability to obtain a cross-sectional view of a target vessel, and exposure of the subject to potentially damaging X-ray radiation.